Circuit breaker



y I943 L. G. RILEY 4 2,323,726

CIRCUIT BREAKER Filed Aug. 22, 19411 2 Sheets-Sheet 1i INVENJTOR LynpGFZ-Jfey; BY] 1 a 5 WITNESSIIEJS: j;

y 1943- LG. RILEY 2,323,726

CIRCUIT BREAKER Filed Aug. 22, 1941 2 Sheets-Sheet 2 Patented July 6, 1943 CIRCUIT BREAKER Lynn G. Riley, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application August 22, 1941, Serial No. 407,918

13 Claims.

This invention relates to circuit breakers and more particularly to contactors for power circuits.

One object of the invention is the provision of a contactor with novel means for dissipating the eifects of impact of the moving contact before contact is established.

Another object of the invention is the provision of an improved circuit breaker construction which eliminates the detrimental effects of impact bouncing or stalling of the movable contact.

Another object of the invention is the provision of an improved circuit breaker construction having means for advancing the point of impact, bounce or stall of the movable contact so that it occurs before the contacts touch, i. e., before the moving contact reaches the danger zone where arcing may occur.

Another object of the invention is to provide a power .oontactor with novel means for initiating a rolling action of the movable contact before contact is established.

Another object of the invention is to provide a circuit breaker with improved means for preventing the contacts from rebounding due to the impact of closing.

Another object of the invention is to provide a circuit breaker having improved means for 1 controlling a pivotally movable contact to prevent rebound uponengagement of the contacts,

and to start a pivoting movement of said contact before engagement with the stationary contact.

Another object of the invention is to provide a circuit breaker having a pivoted contact with means having a greater moment than the con- "tact to dissipate the impact and to impart a 'rotating movement to the contact prior to its thereof when read in conjunction with the accompanying drawings, in which:

Figure l is an elevational View of a part of a circuit breaker embodying the principles of the 'invention, certain members being shown partly broken away to more clearly show the structure. Fig. 2 is a fragmentary elevational view of the contact mechanism in partly closed position.

Fig. 3 is a fragmentary view illustrating a modified form of the invention.

Referring particularly to Figure 1 of the drawings the circuit breaker mechanism is mounted in a frame comprising generally a pair of substantially parallel vertically disposed bars II (only one being shown). These bars are disposed one on each side of a hollow casting l3 and are rigidly secured thereto by meansof bolts l5, the casting I3 being suitably supported on a base structure (not shown). The bars II are surrounded by sheaths l2 of insulating material to form an insulating frame. 7

The upper ends of the bars H are rigidly joined and spaced apart by a member I! of molded insulating material. The member I1 is provided with openings through which the vertical bars ll extend and is secured to said bars by means of set screws l9 tightened against spacers 2| inserted in the opening adjacent the bars ll. Secured to the center portion of the member ll by means of bolts 23 is a horizontally extending bar 25 which is also secured to an arcing horn 21 by means of a bolt 29. The bar 25 extends to the right (Fig. 1) for the purpose of supporting an arcing chamber (not shown). The arcing horn 21 forms an integral part of a casting designated generally by the reference character 3| and which extends across and is secured to the vertical bars H. Across the left hand edges (as viewed in Fig. 1) of the bars ll there extends a cross bar 33 secured to the casting 3i and to the vertical bars II by means of bolts 35. The bolts 35 also serve to rigidly secure a bracket 31 to the cross bar 33.

A conductor 39 is secured to but insulated from the casting 3| by means of a screw 4| which is provided with a bushing 43 and washers 45 of insulating material. The conductor 39 extends to the right (Fig. 1) and is formed into a coil 41 the inner turn of which is divided, the separate-or divided portions 49 of the conductor extending outwardly on opposite sides of the coil and projecting downwardly where they are secured to the casting 3| by means of screws 51. Secured to each of the portions 49 of the conductor 39 by screw bolts 53 is a laminated core member 55 of magnetic material; and a core member 51 also of magneticmaterial secured to the upper ends of the core members 55 by bolts 59 extends through the coil ll, the core member 5'1 being insulated from the coil of a tube 6| by insulating material. The cores 55-5! and the coil 41 form a blow-out electromagnet for and a screw 91.

secure a cam member 99 of insulating material aiding in extinguishing the arc resulting from rupture of the current.

A bolt 53, which serves as a terminal connector, also serves to secure the conductor 39 to an upwardly extending portion 65 of the insulating member IT.

A stationary contact member 61' is secured to a downwardly extending portion of the casting 3| by means of a screw 69. A movable contact 1|, secured by means of a screw 13 to a pivoted,

contact arm 15, is adapted to cooperate with the stationary contact 6'! to open and close the circuit of the breaker. The contact arm is pivoted on a pivot pin 11 supported in upwardly extending arms on a bracket 19 secured to a member 8| of insulating material. The member 8| is secured to the upper end of a piston rod 83 reciprocably mounted in a tubular guide 85 forming a part of the casting I3. The contact arm 15 together with the contact H is biased in a counterclockwise direction to a position slightly inclined from horizontal by means of a spring 81 compressed between the arm 15 and a screw 89 screwed into a recessed portion 9| of the bracket 19. The counterclockwise movement of the contact arm 15 is limited by a portion 93 thereof striking a stop surface on the recessed portion 9| of the bracket 19.

A flexible shunt conductor 94 is secured'to the contact arm 15 by means of a terminal 95 The screw 91 also serves to The contact 1| may be moved into engage-' ment with the stationary contact 81 to efiect closing of the circuit by any suitable operating mechanism. One suitable type of operating -mechanism is disclosed in U. S. Patent No.

1,640,556, granted August 30, 1927, to L. G. Riley .et al. to which reference may be had for a complete understanding of its principles of operation.

,Such an operating mechanism comprises, generally, a piston (not shown) secured on the lower end of the piston rod 83 and adapted to be operated in an upwardly direction to close the contacts by means of air or other suitable fluid under pressure. The admission of air into the cylinder below the piston may be controlled by valves operated magnetically or in any suitable manner. A spring ")3 is provided to open the contacts when the air or other operating medium is vented from the operating mechanism.

'The operating mechanism may also comprise 'a solenoid, electromagnet, or other type of electrical operating device, which may be energized from any suitable source to effect closing of the contacts.

When the piston rod 83 is thrust upwardly, upon admission of fluid under pressure to the operating mechanism, the tip of the contact II will first engage the tip of the stationary contact 61 and a rolling and wiping action will then occur until the heel portions of the contacts 8|-7| are in firm engagement. The rolling and moves the piston rod 83 downwardly to separate the contacts.

The are incident to the rupture of the current is blown outwardly, by the electromagnet comprising the coil 4'1, and the core members 51 and 55, so that the arc is moved outwardly between the arcing horn 21 and a similar arcing horn (not shown) which is associated with the movable contact 1|. An arc extinguisher (not shown) of the type disclosed in the previously mentioned patent to L. G. Riley et al., or any other suitable type may be provided to break up and extinguish the arc.

The contacts of power operated switches have an inherent tendency to rebound or bounce open momentarily due to impact upon closing of the contacts. In the case of pneumatically operated switches the contacts engage before full fluid pressure has been attained and the sudden increase in load causes momentary stalling of the piston which results in the contacts bouncing open and causing heavy arcing and possible welding of the contacts. In magnetically operated switches the closing force increases with contact movement and bouncing of the contacts results from the impact and from the necessity of imparting a rotating motion to the moving contact after the circuit has been established. Another factor contributing to the tendency of the contacts to bounce is the magnetic repulsion between the contacts resulting from the magnetic effect of the power current when the contacts touch but before contact pressure is applied.

The instant invention contemplates means for dissipating the force of the impact and for initiating the pivoting action of the moving contact before contact is actually established between the contacts themselves. The detrimental effects of rebound or stalling are thus removed from the danger zone, and contact is established after the moving contact has started to rotate. The period of initial contact without pressure or movement is thereby eliminated. In order to accomplish this purpose the cam member 99 on the switch arm '15 (Figs. 1 and 2) is provided. This cam cooperates with a roller I05, rotatably mounted on a pivot I01 supported in a pair of arms I09 integral with the bracket 31, upon closing movement of the movable contact structure;

The parts are shown in full lines in Fig. 2 in the position they assume at the instant the cam 99, on its upward travel, engages the roller I05. This occurs before the contact 1| touches the contact 61. The engagement of the cam 99 with the roller I05 dissipates the effect of mechanical bounce or stall before the contacts 1 |-6'| engage and before the movable contact reaches the danger zone, and also starts a clockwise rotation of the contact member 15 about its pivot 11. Continued upward movement of the piston rod 83 causes the contact H to engage the stationary contact 61. As soon as the contacts touch, the continued upward movement of the movable contact assembly causes the cam to immediately disengage the roller I05 due to the fact that the moment arm of the point of engagement of the contacts 6'!'H is less than'the moment of the cam 99. Upon disengagement of the cam 99 from the roller I05 the force produced 'bythe operating mechanism is immediately applied to the movable contact through the spring 81, and the upward movement causes the movable contact to roll and wipe on the stationary contact until only the heel portions of the contacts engage when the breaker reaches the fully closed position.

In the fully closed position the force applied to the piston rod 83 is applied directly to the contacts by means of a face Hl'on bracket 79 engaging a surface H3 on the contact member Since the cam 99 and roller I05 cause the point of impact to occur prior to engagement of the contacts and before the movable contact reaches the danger zone, any bouncing or stall which occurs at this time will not causejarcing. The

detrimental effects of rebound or stall are thus dissipated prior to engagement of the contacts so that when the contacts do engage, substantially no rebound will occur.

When the actuating force is no longer applied to the piston (not shown) the spring I93 acts to lower the piston rod and open the contacts. At the initial downward travel of the contact H the spring 81 causes the contact member l'5'to rotate counterclockwise about its pivot l1 thus effecting a counterclockwise movement ofthe movable contact H from the heel toward the toe of the contacts. This movement continues until the cam member 99 strikes the roller I05 whereupon the pivoting movement is arrested and a substantially straight downward movement is effected. I

Figure 3 illustrates a modified form of the invention in which the cam member 99 and roller I95 are omitted and in place thereof an arm H5 of insulating materialis securedto the contact TI and to the contact member 15 by means of the screw 73, and a stop I I I is provided for operating with they arm H5. The remaining structure is identical to that of the embodiment shown in Fig. 1, and the same reference numerals have been applied to the corresponding parts.

Upon contact closing movement of the piston rod 83 and the movable contact structure, the arm H is moved upwardly and just before contact is established the arm H5 strikes the fixed stop H1. The parts are shown in this position, that is, at the instant the arm H5 strikes the stop I H by dot and dash lines, the position of the arm being indicated at H5a and the position of the movable contact at Ha. Continued upward movement causes the contact member including the contact 'H and arm H5 to rotate in a clockwise direction about the pivot 1'! while said pivot continues its upward travel. The impact is thereby effectively dissipated and the contact 1| is caused to start its pivoting movement prior to engagement with the stationary contact. After the contacts engage, the arm H5 disengages the stop l I"! and the movable contact rolls and slides on the fixed contact until the fully closed position is reached. The parts are illustrated by dot and dash lines Nb and H517 in Figure 3 in their fully closed position.

When the mechanism moves to open the contacts the reverse rolling and sliding movement of the movable contact H, effected by the spring 81, brings the arm I I5 into contact with the fixed stop H! which causes separation of the contacts while the rolling movement of the contact 1| is in progress. Continued downward movement of the mechanism quickly moves the movable contact to its full open position.

Having described several embodiments of the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the structural details disclosed without departing from some of the essential features of the invention. It is, therefore, desired that the language of the appended claims be given as reasonably broad interpretation as the prior art permits.

I claim as my invention:

1. A switch comprising a stationar contact, a movable contact, an actuating member movable to open and close the contacts, said movable contact being movable to open and to closed position in a path at right angles to the surface of engagement of said contacts, and means insulated from one of said contacts and operable prior to engagement of the contacts to cause an impact of the movable contact before the contacts engage.

2'. In a circuit breaker, separable contacts, a reciprocable member movable to open and close the contacts, a switch arm pivotally supported on said reciprocable member, one of said contacts being mounted on the switch arm, a fixed member mounted independently of said contacts, and

'means on said switch arm engageable with said fixed member prior to engagement of the contacts to retard closing movement of the contacts before the circuit is established.

3. In a circuit breaker, relatively movable con- .tacts, an actuating member movable to open and close the contacts, one of said contacts being pivotally supported on the actuating member, a fixed member mounted independently of said contacts, and means cooperating with said fixed member at a predetermined time prior to engagement of the contacts for advancing the point of impact to dissipate the kinetic energy before the circuit is established.

4. A circuit breaker comprising a supporting frame, relatively movable contacts, a reciprocable actuating means movable to open and close the contacts, a switch member pivotally supported on the actuating means, a projection on the witch member, and non-current carrying means mounted on said frame and disposed to engage said projection when the actuating means moves to close the contacts for producing an impact before engagement of the contacts without imposing additional load on the actuating means.

5. A circuit breaker comprising a pair of separable contacts, an actuating member movable to open and close the contacts, a switch member pivotally supported on the actuating member, one of said contacts being mounted on the switch member, a cam on the switch member, and means mounted independently of said contacts and engageable by said cam at a predetermined time prior to engagement of the contacts for retarding the closing movement of the contacts before said contacts touch.

6. In a circuit breaker, a stationary contact, a movable contact, an actuating member movable to open and close the contacts, a switch member pivotally supported on the actuating member and carrying said movable contact, said switch member pivoting to effect a rolling and wiping action of said contacts upon engagement of said contacts, and means partly on said switch member operable during the closing movement of the actuating member to initiate the pivoting action before engagement of the contacts, said last mentioned means being insulated from at least one of said contacts.

7. A circuit breaker, comprising a pair of cooperating contacts, at least one of which is movable, actuating means for opening and closing said contacts, a switch member pivotally supported on said actuating means, said switch member being operable upon engagement of said conally supported on said actuating member, said switch member being operable upon movement of the actuating member to closed position to cause a rolling engagement of said contacts, a non-current carrying cam member mounted on the switch member, and means mounted separate from said contacts and engageable by said cam member at a predetermined time during the closing movement of the actuating member to cause impact of one of the contacts and to initiate the pivoting action of said contact before the circuit is established.

9. A circuit breaker comprising a movable contact and a stationary contact, an actuating member movable to open and close said contacts, a switch member pivotally supported on said actuating member, said movable contact being mounted on the switch member, a non-current carrying cam member mounted on the switch member, and a roller mounted in a fixed support, said roller being engageable by said cam before engagement of the contacts to absorb a part of the kinetic energy of the moving parts before the contacts touch.

10. A circuit breaker comprising a single pair of cooperating contacts, at least one of which is movable, actuating means operable to open and close said contacts, a pivoted switch member on said actuating means for supporting the movable contact, said switch member being operable upon engagement of the contacts to eiTect a rolling engagement of said contacts, a non-current carrying projection on the switch member, and fixed means mounted independently of said contacts and engageable by said projection prior to engagement of the contacts for effecting an impact before the contacts touch, said contacts constituting the sole means for opening and closing the circuit.

11. An electrical circuit interrupter comprising a pair of cooperating contacts at least one of which is movable to open and to closed position in a path substantially at right angles to the surface'of engagement of said contacts, operating means for opening and closing said contacts, and non-current carrying means engageable by a part movable with said movable contact prior to engagement of said contacts for absorbing a portion of the kinetic energy of the moving parts.

12. An electrical circuit interrupter comprising a stationary contact, a movable contact assembly, a pivoted contact arm on said movable contact assembly said contact arm carrying a movable contact for cooperating with the stationary contact, operating mechanism for moving the movable contact assembly to open and to closed circuit position, and a non-current carrying member engageable by a part on said contact arm prior to engagement of said contacts for absorbing a portion of the kinetic energy of the contact arm without imposing substantially any additional load'on the operating mechanism to close the breaker.

13. In an electrical circuit interrupter comprising separable contacts, a movable contact arm carrying one of said contacts, said contact being movable at right angles to the surface of engagement of the contacts, operating means for opening and closing the contacts, and means ngageable by a member on said contact arm prior to engagement of said contacts for effecting an impact before the contacts touch, said member being insulated from said contact arm, said contact arm disengaging said engageable means after the contacts touch.

LYNN G. RILEY. 

